The invention relates to a self-adjusting device that equalizes length.
Self-adjusting devices that equalize length are known in various embodiments. Thus, there are spring-loaded tension rollers that keep a traction rope taut. With tension rollers of that type, however, neither an equalization of differing rope lengths due to production tolerances, nor a lasting extension of rope which occurs with use over a period of time, can be compensated. This is particularly problematical in the case of traction ropes for the activation of locking latches on seats in motor vehicles. Due to the fact that such locking latches are customarily provided on two different sides of the folding back rest, they must be adjusted and synchronized very precisely. Doing so is time-consuming. In addition, unequal changes in the length of the traction ropes that lead to different locking latches, changes which are altogether possible, have the disadvantageous consequence that after a period of use, the two locking levers no longer release the locking bolts on the seat parts simultaneously. In addition, as a result of changes in the length of the traction rope, the initial position of the activation lever is changed, with the consequence that in the extreme case, the remainder of the path of position adjustment of the activation element is no longer sufficient to release the locking latch.
A device for equalizing length, which joins adjacent ends of a tractile element, such as a pull wire or a traction rope, is already known from for example, U.S. Pat. No. 4,448,090. In such device one end is connected to a terminal element that assumes the form of a pin and is under pre-stress in the direction of its axis by means of a compression spring; the other end is connected with a yoke, on which a clamping rocker that is under pre-stress by means of a spring is seated so that it can pivot. Under the force of the spring, the clamping rocker is held snugly, with its clamping surface against the outer circumference of the terminal element, which is in the form of a pin. A critical disadvantage of this known length-equalizing device resides in the fact that it may not be used for continuous pull ropes, but only for discontinuous ones.
An adjustment device is known, furthermore, (U.S. Pat. No. 3,365,978) in which two areas of a tightening element that may be swiveled are partially entwined by a continuous pull ropes. This adjustment device serves neither as a device that equalizes the length of pull ropes, nor is it automatically self-adjusting. Rather, the tension element, which may be pivoted, serves to generate a pre-selected position of a tool that is to be operated.
It is an object of the invention to create a self-adjusting device that equalizes length for a continuous pull rope that operates parts of motor vehicles, and in particular, for locking latches of motor vehicle seats, by means of which the initial position of the activation element is kept constant, so that apparatus that equalizes length may be constructed in a simple and cost-effective manner.